Process for preparing modified ardealite by water-free calcining

A phosphogypsum, waterless washing technology, used in building materials and phosphorus chemical industry, can solve the problems of large one-time investment in pretreatment process, serious secondary pollution of sewage discharge, lack of competitiveness, etc. , The effect of reducing energy consumption and avoiding secondary pollution

Inactive Publication Date: 2008-11-19
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The above-mentioned process has problems such as large one-time investment in pretreatment process, high energy consumption, serious secondar

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] According to the weight proportion of 91% phosphogypsum, 1% green vitriol, 1% aluminum sulfate, 2% quicklime, and 5% cement, mix them evenly, and dry them in a dryer. The drying temperature is controlled at 105°C, and the The moisture content of phosphogypsum is lower than 8%, and then enters the calciner to be calcined at 200°C. The high-temperature flue gas generated during the calcination process is recovered to a dryer to dry the phosphogypsum, and after 0.5 hours of calcination, the heating of the calcination furnace is stopped, and the modified phosphogypsum is obtained by natural cooling.

[0031] The measured product performance is as follows:

[0032] SO 3 Content 45%;

[0033] The fluoride ion concentration in the leachate is 0.4mg / L;

[0034] Standard consistency 60%;

[0035] The initial setting time is 7min;

[0036] The final setting time is 28min;

[0037] Flexural strength 2.6Mpa;

[0038] Compressive strength 5.1Mpa;

[0039] It meets the requir...

Embodiment 2

[0041] 91% of phosphogypsum, 1.5% of green vitriol, 1.5% of aluminum sulfate, 2% of quicklime, and 4% of cement are mixed evenly and dried in a dryer. The drying temperature is controlled at 105°C and made Phosphogypsum moisture is less than 8%. Then enter the calciner for calcination at 300°C. The high-temperature flue gas generated during the calcination process is recovered to a dryer to dry the phosphogypsum, and after 0.5 hours of calcination, the heating of the calcination furnace is stopped, and the modified phosphogypsum is obtained by natural cooling.

[0042] The measured product performance is as follows:

[0043] SO 3 Content 46%,

[0044] The fluoride ion concentration in the leachate is 0.35mg / L,

[0045] Standard consistency 60%,

[0046] Initial setting time 8min,

[0047] The final setting time is 29min,

[0048] Flexural strength 2.7Mpa,

[0049] Compressive strength 5.4Mpa,

[0050] It meets the requirements of "Building Materials Gypsum" GB9776-88 fo...

Embodiment 3

[0052] According to the weight ratio of 85% phosphogypsum, 2% green vitriol, 3% aluminum sulfate, 3% quicklime, and 7% cement, mix them evenly, and dry them in a dryer. The drying temperature is controlled at 105 ° C, and the Phosphogypsum moisture is less than 8%. Then enter the calciner for calcination at 200°C. The high-temperature flue gas generated during the calcination process is recovered to a dryer to dry the phosphogypsum, and after 0.5 hours of calcination, the heating of the calcination furnace is stopped, and the modified phosphogypsum is obtained by natural cooling.

[0053] The measured product performance is as follows:

[0054] SO 3 Content 46%,

[0055] The fluoride ion concentration in the leach solution is 0.42mg / L,

[0056] Standard consistency 61%,

[0057] Initial setting time 10min,

[0058] The final setting time is 30min,

[0059] Flexural strength 2.8Mpa,

[0060] Compressive strength 5.5Mpa,

[0061] It meets the requirements of "Building M...

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Abstract

The invention relates to a method for preparing modified phosphogypsum through calcination without water scrubbing. The method is as follows: firstly, composite excitant and modifier are added into phosphogypsum and uniformly mixed, wherein, the weight percent of the phosphogypsum is between 85 and 95 percent; the weight percent of the composite excitant is between 2 and 5 percent; the weight percent of the modifier is between 3 and 10 percent; the composite excitant is green vitriol and aluminum sulphate, and the modifier is calcium oxide and cement; secondly, after uniform mixing, the mixture is dried at a drying temperature of between 100 and 110 DEG C, and the moisture of the phosphogypsum is lower than 8 percent; thirdly, the mixture enters into a calciner, is calcined for 0.5 to 1 hour at a temperature of between 150 and 300 DEG C, and is naturally cooled to prepare the modified phosphogypsum. The method decomposes and volatilizes harmful substances such as phosphor, fluorine, organic substances and so on contained in the phosphogypsum or converts the harmful substances into inert substance calcium pyrophosphate which is harmless to products, thereby not only avoiding secondary pollution but also reducing or avoiding influence of harmful chemical microconstituents contained in the phosphogypsum on the quality and the performance of the products. Moreover, the method shortens the processing time by 15 to 20 percent, saves the investment by 3 to 8 percent and reduces the energy consumption by 10 to 20 percent.

Description

technical field [0001] The invention relates to the technical fields of phosphorus chemical industry and building materials, and specifically describes a method for preparing modified phosphogypsum by calcining without water washing. Background technique [0002] Phosphogypsum is the industrial waste produced by the reaction of phosphate rock and sulfuric acid in the production process of wet-process phosphoric acid. It is calculated that every ton of phosphoric acid produced will produce 4-5 tons of phosphogypsum. At present, the annual discharge of phosphogypsum in the world reaches 200 million Tons, but the utilization rate of phosphogypsum is not more than 10%. The treatment, disposal and comprehensive utilization of phosphogypsum has become a worldwide problem. my country's phosphate fertilizer output ranks first in the world. The production of high-concentration phosphate fertilizers (such as ammonium phosphate, heavy calcium, etc.) requires a large amount of wet-proce...

Claims

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Application Information

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IPC IPC(8): C04B11/26
Inventor 杨月红方祖国宁平张慧娜欧根能
Owner KUNMING UNIV OF SCI & TECH
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